Unless otherwise indicated herein, the description provided in this section is not itself prior art to the claims and is not admitted to be prior art by inclusion in this section.
A typical cellular wireless network includes a number of base stations each radiating to define a respective coverage area in which user equipment devices (UEs) such as cell phones, tablet computers, tracking devices, embedded wireless modules, and other wirelessly equipped communication devices, can operate. In particular, each coverage area may operate on one or more carriers each defining a respective frequency bandwidth of coverage. In turn, each base station may be coupled with network infrastructure that provides connectivity with one or more transport networks, such as the public switched telephone network (PSTN) and/or the Internet for instance. With this arrangement, a UE within coverage of the network may engage in air interface communication with a base station and may thereby communicate via the base station with various remote network entities or with other UEs served by the base station.
Further, a cellular wireless network may operate in accordance with a particular air interface protocol or “radio access technology,” with communications from the base stations to UEs defining a downlink or forward link and communications from the UEs to the base stations defining an uplink or reverse link. Examples of existing air interface protocols include, without limitation, Orthogonal Frequency Division Multiple Access (OFDMA (e.g., Long Term Evolution (LTE) and Wireless Interoperability for Microwave Access (WiMAX)), Code Division Multiple Access (CDMA) (e.g., 1×RTT and 1×EV-DO), and Global System for Mobile Communications (GSM), among others. Each protocol may define its own procedures for registration of UEs, initiation of communications, handover between coverage areas, and other functions related to air interface communication.
In accordance with the air interface protocol, each coverage area may define a number of channels or specific resources for carrying signals and information between the base station and UEs. For instance, certain resources on the downlink may be reserved to carry a reference signal that UEs may detect as an indication of coverage and may measure to evaluate coverage quality, other resources on the downlink may be reserved to carry other control signaling to UEs, and still other resources on the downlink may be reserved to carry bearer traffic and other such communications to UEs. Likewise, certain resources on the uplink may be reserved to carry various control signaling from UEs to the base station, and other resources on the uplink may be reserved to carry bearer traffic and other such communications from UEs.
When a UE is served by a base station, the base station and/or associated network infrastructure may maintain a “neighbor list” that indicates other nearby base stations to which UEs being served by the base station could potentially hand over. Such a neighbor list could specify various information about each such handover neighbor, including for instance one or more coverage frequencies on which the neighbor operates, a network address of the neighbor, and a geographic location of the neighbor. In practice, such neighbor data could be updated from time to time as changes are made in the configuration of the network, such as when base stations are added, removed, moved, or reconfigured. For instance, the neighbor data could be updated manually by engineering input as changes are made to the network and/or through an automated process as UEs report various detected neighbors.
Further, when the UE is served by the base station, the UE may regularly monitor the reference signal from that base station and reference signals from other base stations in the vicinity, to help ensure that the UE continues to operate in a most appropriate coverage area. If the UE finds that one or more other base stations provide sufficiently strong coverage, perhaps sufficiently stronger than the UE's currently serving base station, then the UE may initiate handover. For instance, the UE may transmit to its serving base station a measurement report that specifies the one or more detected coverage areas and, for each such coverage area, the detected signal strength. The serving base station (source base station) and/or associated network infrastructure may then decide based on the UE's measurement report to process a handover of the UE to a particular base station (target base station) from which the UE detected sufficiently strong signal strength.